Plasticizers are compounds or mixtures of compounds that are added to polymer resins to impart softness and flexibility. Phthalic acid diesters (also known as “phthalates”) are known plasticizers in many flexible polymer products, such as polymer products formed from polyvinyl chloride (PVC) and other vinyl polymers. Examples of common phthalate plasticizers include di-isononyl phthalate (DINP), diallyl phthalate (DAP), di-2-ethylhexyl-phthalate (DEHP), dioctyl phthalate (DOP) and diisodecyl phthalate (DIDP). Other common plasticizers, used for high temperature applications, are trimellitates and adipic polyesters. Mixtures of plasticizers are often used to obtain optimum properties.
Phthalate plasticizers have recently come under intense scrutiny by public interest groups that are concerned about the negative environmental impact of phthalates and potential adverse health effects in humans (especially children) exposed to phthalates.
A known phthalate-free plasticizer for use in polyvinyl chloride (PVC) formulations is epoxidized soy oil. Unfortunately, epoxidized soy oil has limited solubility in PVC and insufficiently plasticizes PVC at low temperature (i.e., −20° C. and lower). PVC plasticized with epoxidized soy oil also exhibits a phenomenon called ‘spew’ which is a migration of the epoxidized soy oil to the PVC surface over time. Spew results in a more rigid PVC with a slippery surface. The spew phenomenon can result in brittleness and failure of the PVC.
The art recognizes the need to broaden applications for plasticized PVC that are phthalate-free, and/or plasticizers having less phthalate than conventional plasticizers. Accordingly, a need exists for a plasticizer with reduced, or no, phthalate for polymer resin which can withstand the low temperature unwind test. A need further exists for a plasticized polymeric composition with reduced, or no, phthalate, the polymeric composition having weight retention when exposed to temperature above ambient.